The structure of a conventional capacitance type dynamic quantity sensor formed on a semiconductor substrate has recently been designed to be higher in density and more complicated to satisfy the requirements of high precision and high sensitivity. Therefore, it is very difficult to perform visual examination at each of the sites corresponding to the constituent elements of the sensor.
Also, the capacitance type dynamic quantity sensor as described above has problems in quality resulting from adherence of foreign material. Particularly, when foreign material becomes invisible in a hollow portion between a movable portion and a semiconductor substrate, the foreign material concerned cannot be detected by visual examination using visible light. Therefore, there is a risk that foreign material is adhered to the sensor in the gap between a movable portion (movable electrode, poise portion) and a fixed electrode and the gap between a movable portion and a semiconductor substrate, to thereby prevent normal operation.
A method of detecting foreign material hidden between a movable portion and a semiconductor substrate has been disclosed in which an infrared ray or the like is transmitted through the movable portion with a detector.
However, even when the foreign material is detected by the detector described above, it is difficult to remove the foreign material hidden between the movable portion and the semiconductor substrate, thus resulting in a defective sensor containing such foreign material.